Planning for resilience: Incorporating scenario and model uncertainty and trade-offs when prioritizing management of climate refugia.

Climate change has become the greatest threat to the world's ecosystems. Locating and managing areas that contribute to the survival of key species under climate change is critical for the persistence of ecosystems in the future. Here, we identify 'Climate Priority' sites as coral reefs exposed to relatively low levels of climate stress that will be more likely to persist in the future. We present the first analysis of uncertainty in climate change scenarios and models, along with multiple objectives, in a marine spatial planning exercise and offer a comprehensive approach to incorporating uncertainty and trade-offs in any ecosystem. We first described each site using environmental characteristics that are associated with a higher chance of persistence (larval connectivity, hurricane influence, and acute and chronic temperature conditions in the past and the future). Future temperature increases were assessed using downscaled data under four different climate scenarios (SSP1 2.6, SSP2 4.5, SSP3 7.0 and SSP5 8.5) and 57 model runs. We then prioritized sites for intervention (conservation, improved management or restoration) using robust decision-making approaches that select sites that will have a benign climate under most climate scenarios and models. The modelling work is novel because it solves two important issues. (1) It considers trade-offs between multiple planning objectives explicitly through Pareto analyses and (2) It makes use of all the uncertainty around future climate change. Priority intervention sites identified by the model were verified and refined through local stakeholder engagement including assessments of local threats, ecological conditions and government priorities. The workflow is presented for the Insular Caribbean and Florida, and at the national level for Cuba, Jamaica, Dominican Republic and Haiti. Our approach allows managers to consider uncertainty and multiple objectives for climate-smart spatial management in coral reefs or any ecosystem across the globe.

Challenges to natural and human communities from surprising ocean temperatures.

The community of species, human institutions, and human activities at a given location have been shaped by historical conditions (both mean and variability) at that location. Anthropogenic climate change is now adding strong trends on top of existing natural variability. These trends elevate the frequency of "surprises"-conditions that are unexpected based on recent history. Here, we show that the frequency of surprising ocean temperatures has increased even faster than expected based on recent temperature trends. Using a simple model of human adaptation, we show that these surprises will increasingly challenge natural modes of adaptation that rely on historical experience. We also show that warming rates are likely to shift natural communities toward generalist species, reducing their productivity and diversity. Our work demonstrates increasing benefits for individuals and institutions from betting that trends will continue, but this strategy represents a radical shift that will be difficult for many to make.

Connectivity and systemic resilience of the Great Barrier Reef.

Australia's iconic Great Barrier Reef (GBR) continues to suffer from repeated impacts of cyclones, coral bleaching, and outbreaks of the coral-eating crown-of-thorns starfish (COTS), losing much of its coral cover in the process. This raises the question of the ecosystem's systemic resilience and its ability to rebound after large-scale population loss. Here, we reveal that around 100 reefs of the GBR, or around 3%, have the ideal properties to facilitate recovery of disturbed areas, thereby imparting a level of systemic resilience and aiding its continued recovery. These reefs (1) are highly connected by ocean currents to the wider reef network, (2) have a relatively low risk of exposure to disturbances so that they are likely to provide replenishment when other reefs are depleted, and (3) have an ability to promote recovery of desirable species but are unlikely to either experience or spread COTS outbreaks. The great replenishment potential of these 'robust source reefs', which may supply 47% of the ecosystem in a single dispersal event, emerges from the interaction between oceanographic conditions and geographic location, a process that is likely to be repeated in other reef systems. Such natural resilience of reef systems will become increasingly important as the frequency of disturbances accelerates under climate change.

Spatial resilience of the Great Barrier Reef under cumulative disturbance impacts.

In the face of increasing cumulative effects from human and natural disturbances, sustaining coral reefs will require a deeper understanding of the drivers of coral resilience in space and time. Here we develop a high-resolution, spatially explicit model of coral dynamics on Australia's Great Barrier Reef (GBR). Our model accounts for biological, ecological and environmental processes, as well as spatial variation in water quality and the cumulative effects of coral diseases, bleaching, outbreaks of crown-of-thorns starfish (Acanthaster cf. solaris), and tropical cyclones. Our projections reconstruct coral cover trajectories between 1996 and 2017 over a total reef area of 14,780 km2 , predicting a mean annual coral loss of -0.67%/year mostly due to the impact of cyclones, followed by starfish outbreaks and coral bleaching. Coral growth rate was the highest for outer shelf coral communities characterized by digitate and tabulate Acropora spp. and exposed to low seasonal variations in salinity and sea surface temperature, and the lowest for inner-shelf communities exposed to reduced water quality. We show that coral resilience (defined as the net effect of resistance and recovery following disturbance) was negatively related to the frequency of river plume conditions, and to reef accessibility to a lesser extent. Surprisingly, reef resilience was substantially lower within no-take marine protected areas, however this difference was mostly driven by the effect of water quality. Our model provides a new validated, spatially explicit platform for identifying the reefs that face the greatest risk of biodiversity loss, and those that have the highest chances to persist under increasing disturbance regimes.

Vulnerability of the Great Barrier Reef to climate change and local pressures.

Australia's Great Barrier Reef (GBR) is under pressure from a suite of stressors including cyclones, crown-of-thorns starfish (COTS), nutrients from river run-off and warming events that drive mass coral bleaching. Two key questions are: how vulnerable will the GBR be to future environmental scenarios, and to what extent can local management actions lower vulnerability in the face of climate change? To address these questions, we use a simple empirical and mechanistic coral model to explore six scenarios that represent plausible combinations of climate change projections (from four Representative Concentration Pathways, RCPs), cyclones and local stressors. Projections (2017-2050) indicate significant potential for coral recovery in the near-term, relative to current state, followed by climate-driven decline. Under a scenario of unmitigated emissions (RCP8.5) and business-as-usual management of local stressors, mean coral cover on the GBR is predicted to recover over the next decade and then rapidly decline to only 3% by year 2050. In contrast, a scenario of strong carbon mitigation (RCP2.6) and improved water quality, predicts significant coral recovery over the next two decades, followed by a relatively modest climate-driven decline that sustained coral cover above 26% by 2050. In an analysis of the impacts of cumulative stressors on coral cover relative to potential coral cover in the absence of such impacts, we found that GBR-wide reef performance will decline 27%-74% depending on the scenario. Up to 66% of performance loss is attributable to local stressors. The potential for management to reduce vulnerability, measured here as the mean number of years coral cover can be kept above 30%, is spatially variable. Management strategies that alleviate cumulative impacts have the potential to reduce the vulnerability of some midshelf reefs in the central GBR by 83%, but only if combined with strong mitigation of carbon emissions.

Controlling range expansion in habitat networks by adaptively targeting source populations.

Controlling the spread of invasive species, pests, and pathogens is often logistically limited to interventions that target specific locations at specific periods. However, in complex, highly connected systems, such as marine environments connected by ocean currents, populations spread dynamically in both space and time via transient connectivity links. This results in nondeterministic future distributions of species in which local populations emerge dynamically and concurrently over a large area. The challenge, therefore, is to choose intervention locations that will maximize the effectiveness of the control efforts. We propose a novel method to manage dynamic species invasions and outbreaks that identifies the intervention locations most likely to curtail population expansion by selectively targeting local populations most likely to expand their future range. Critically, at any point during the development of the invasion or outbreak, the method identifies the local intervention that maximizes the long-term benefit across the ecosystem by restricting species' potential to spread. In so doing, the method adaptively selects the intervention targets under dynamically changing circumstances. To illustrate the effectiveness of the method we applied it to controlling the spread of crown-of-thorns starfish (Acanthaster sp.) outbreaks across Australia's Great Barrier Reef. Application of our method resulted in an 18-fold relative improvement in management outcomes compared with a random targeting of reefs in putative starfish control scenarios. Although we focused on applying the method to reducing the spread of an unwanted species, it can also be used to facilitate the spread of desirable species through connectivity networks. For example, the method could be used to select those fragments of habitat most likely to rebuild a population if they were sufficiently well protected.

Global inequities between polluters and the polluted: climate change impacts on coral reefs.

For many ecosystem services, it remains uncertain whether the impacts of climate change will be mostly negative or positive and how these changes will be geographically distributed. These unknowns hamper the identification of regional winners and losers, which can influence debate over climate policy. Here, we use coral reefs to explore the spatial variability of climate stress by modelling the ecological impacts of rising sea temperatures and ocean acidification, two important coral stressors associated with increasing greenhouse gas (GHG) emissions. We then combine these results with national per capita emissions to quantify inequities arising from the distribution of cause (CO2 emissions) and effect (stress upon reefs) among coral reef countries. We find pollution and coral stress are spatially decoupled, creating substantial inequity of impacts as a function of emissions. We then consider the implications of such inequity for international climate policy. Targets for GHG reductions are likely to be tied to a country's emissions. Yet within a given level of GHG emissions, our analysis reveals that some countries experience relatively high levels of impact and will likely experience greater financial cost in terms of lost ecosystem productivity and more extensive adaptation measures. We suggest countries so disadvantaged be given access to international adaptation funds proportionate with impacts to their ecosystem. We raise the idea that funds could be more equitably allocated by formally including a metric of equity within a vulnerability framework.

Anticipative management for coral reef ecosystem services in the 21st century.

Under projections of global climate change and other stressors, significant changes in the ecology, structure and function of coral reefs are predicted. Current management strategies tend to look to the past to set goals, focusing on halting declines and restoring baseline conditions. Here, we explore a complementary approach to decision making that is based on the anticipation of future changes in ecosystem state, function and services. Reviewing the existing literature and utilizing a scenario planning approach, we explore how the structure of coral reef communities might change in the future in response to global climate change and overfishing. We incorporate uncertainties in our predictions by considering heterogeneity in reef types in relation to structural complexity and primary productivity. We examine 14 ecosystem services provided by reefs, and rate their sensitivity to a range of future scenarios and management options. Our predictions suggest that the efficacy of management is highly dependent on biophysical characteristics and reef state. Reserves are currently widely used and are predicted to remain effective for reefs with high structural complexity. However, when complexity is lost, maximizing service provision requires a broader portfolio of management approaches, including the provision of artificial complexity, coral restoration, fish aggregation devices and herbivore management. Increased use of such management tools will require capacity building and technique refinement and we therefore conclude that diversification of our management toolbox should be considered urgently to prepare for the challenges of managing reefs into the 21st century.

Accounting for albedo change to identify climate-positive tree cover restoration.

Restoring tree cover changes albedo, which is the fraction of sunlight reflected from the Earth's surface. In most locations, these changes in albedo offset or even negate the carbon removal benefits with the latter leading to global warming. Previous efforts to quantify the global climate mitigation benefit of restoring tree cover have not accounted robustly for albedo given a lack of spatially explicit data. Here we produce maps that show that carbon-only estimates may be up to 81% too high. While dryland and boreal settings have especially severe albedo offsets, it is possible to find places that provide net-positive climate mitigation benefits in all biomes. We further find that on-the-ground projects are concentrated in these more climate-positive locations, but that the majority still face at least a 20% albedo offset. Thus, strategically deploying restoration of tree cover for maximum climate benefit requires accounting for albedo change and we provide the tools to do so.

Consistent cooling benefits of silvopasture in the tropics.

Agroforestry systems have the potential to sequester carbon and offer numerous benefits to rural communities, but their capacity to offer valuable cooling services has not been quantified on continental scales. Here, we find that trees in pasturelands ("silvopasture") across Latin America and Africa can offer substantial cooling benefits. These cooling benefits increase linearly by -0.32 °C to -2.4 °C per 10 metric tons of woody carbon per hectare, and importantly do not depend on the spatial extent of the silvopasture systems. Thus, even smallholders can reap important cooling services from intensifying their silvopasture practices. We then map where realistic (but ambitious) silvopasture expansion could counteract a substantial fraction of the local projected warming in 2050 due to climate change. Our findings indicate where and to what extent silvopasture systems can counteract local temperature increases from global climate change and help vulnerable communities adapt to a warming world.

Wildfire, Smoke Exposure, Human Health, and Environmental Justice Need to be Integrated into Forest Restoration and Management.

PURPOSE OF REVIEW: Increasing wildfire size and severity across the western United States has created an environmental and social crisis that must be approached from a transdisciplinary perspective. Climate change and more than a century of fire exclusion and wildfire suppression have led to contemporary wildfires with more severe environmental impacts and human smoke exposure. Wildfires increase smoke exposure for broad swaths of the US population, though outdoor workers and socially disadvantaged groups with limited adaptive capacity can be disproportionally exposed. Exposure to wildfire smoke is associated with a range of health impacts in children and adults, including exacerbation of existing respiratory diseases such as asthma and chronic obstructive pulmonary disease, worse birth outcomes, and cardiovascular events. Seasonally dry forests in Washington, Oregon, and California can benefit from ecological restoration as a way to adapt forests to climate change and reduce smoke impacts on affected communities. RECENT FINDINGS: Each wildfire season, large smoke events, and their adverse impacts on human health receive considerable attention from both the public and policymakers. The severity of recent wildfire seasons has state and federal governments outlining budgets and prioritizing policies to combat the worsening crisis. This surging attention provides an opportunity to outline the actions needed now to advance research and practice on conservation, economic, environmental justice, and public health interests, as well as the trade-offs that must be considered. Scientists, planners, foresters and fire managers, fire safety, air quality, and public health practitioners must collaboratively work together. This article is the result of a series of transdisciplinary conversations to find common ground and subsequently provide a holistic view of how forest and fire management intersect with human health through the impacts of smoke and articulate the need for an integrated approach to both planning and practice.

Warming from tropical deforestation reduces worker productivity in rural communities.

The accelerating loss of tropical forests in the 21st century has eliminated cooling services provided by trees in low latitude countries. Cooling services can protect rural communities and outdoor workers with little adaptive capacity from adverse heat exposure, which is expected to increase with climate change. Yet little is still known about whether cooling services can mitigate negative impacts of heat on labor productivity among rural outdoor workers. Through a field experiment in Indonesia, we show that worker productivity was 8.22% lower in deforested relative to forested settings, where wet bulb globe temperatures were, on average, 2.84 °C higher in deforested settings. We demonstrate that productivity losses are driven by behavioral adaptations in the form of increased number of work breaks, and provide evidence that suggests breaks are in part driven by awareness of heat effects on work. Our results indicate that the cooling services from forests have the potential for increasing resilience and adaptive capacity to local warming.

The effect of deforestation and climate change on all-cause mortality and unsafe work conditions due to heat exposure in Berau, Indonesia: a modelling study.

BACKGROUND: Previous studies focusing on urban, industrialised regions have found that excess heat exposure can increase all-cause mortality, heat-related illnesses, and occupational injuries. However, little research has examined how deforestation and climate change can adversely affect work conditions and population health in low latitude, industrialising countries. METHODS: For this modelling study we used data at 1 km2 resolution to compare forest cover and temperature conditions in the Berau regency, Indonesia, between 2002 and 2018. We used spatially explicit satellite, climate model, and population data to estimate the effects of global warming, between 2002 and 2018 and after applying 1·0°C, 1·5°C, and 2·0°C of global warming to 2018 temperatures, on all-cause mortality and unsafe work conditions in the Berau regency, Indonesia. FINDINGS: Between 2002 and 2018, 4375 km2 of forested land in Berau was cleared, corresponding to approximately 17% of the entire regency. Deforestation increased mean daily maximum temperatures by 0·95°C (95% CI 0·97-0·92; p<0·0001). Mean daily temperatures increased by a population-weighted 0·86°C, accounting for an estimated 7·3-8·5% of all-cause mortality (or 101-118 additional deaths per year) in 2018. Unsafe work time increased by 0·31 h per day (95% CI 0·30-0·32; p<0·0001) in deforested areas compared to 0·03 h per day (0·03-0·04; p<0·0001) in areas that maintained forest cover. With 2·0°C of additional future global warming, relative to 2018, deforested areas could experience an estimated 17-20% increase in all-cause mortality (corresponding to an additional 236-282 deaths per year) and up to 5 h of unsafe work per day. INTERPRETATION: Heat exposure from deforestation and climate change has already started affecting populations in low latitude, industrialising countries, and future global warming indicates substantial health impacts in these regions. Further research should examine how deforestation is currently affecting the health and wellbeing of local communities. FUNDING: University of Washington Population Health Initiative. TRANSLATION: For the Bahasa translation of the abstract see Supplementary Materials section.

Prioritizing actions: spatial action maps for conservation.

Spatial prioritization is a critical step in conservation planning, a process designed to ensure that limited resources are applied in ways that deliver the highest possible returns for biodiversity and human wellbeing. In practice, many spatial prioritizations fall short of their potential by focusing on places rather than actions, and by using data of snapshots of assets or threats rather than estimated impacts. We introduce spatial action mapping as an approach that overcomes these shortfalls. This approach produces a spatially explicit view of where and how much a given conservation action is likely to contribute to achieving stated conservation goals. Through seven case examples, we demonstrate simple to complex versions of how this method can be applied across local to global scales to inform decisions about a wide range of conservation actions and benefits. Spatial action mapping can support major improvements in efficient use of conservation resources and will reach its full potential as the quality of environmental, social, and economic datasets converge and conservation impact evaluations improve.

Heat Exposure and Occupational Injuries: Review of the Literature and Implications.

PURPOSE OF REVIEW: The burden of heat-related adverse occupational health effects, as well as traumatic injuries, is already substantial. Projected increases in mean temperatures and extreme events may increase the risk of adverse heat health effects and enhance disparities among exposed workers. This article reviews the emerging literature on the relationship between heat exposure and occupational traumatic injuries and discusses implications of this work. RECENT FINDINGS: A recent meta-analysis of three case-crossover and five time series studies in industrialized settings reported an association of increasing occupational injuries with increasing heat exposure, with increased effect estimates for male gender and age less than 25 years, although heterogeneity in exposure metrics and sources of bias were demonstrated to varying degrees across studies. A subsequent case-crossover study in outdoor construction workers reported a 0.5% increase in the odds of traumatic injuries per 1 °C increase in maximum daily humidex (odds ratio 1.005 [95% CI 1.003-1.007]). While some studies have demonstrated reversed U-shaped associations between heat exposure and occupational injuries, different risk profiles have been reported in different industries and settings. Studies conducted primarily in industrialized settings suggest an increased risk of traumatic injury with increasing heat exposure, though the exact mechanisms of heat exposure's effects on traumatic injuries are still under investigation. The effectiveness of heat-related injury prevention approaches has not yet been established. To enhance the effectiveness of prevention efforts, prioritization of approaches should take into account not only the hierarchy of controls, social-ecological models, community and stakeholder participation, and tailoring of approaches to specific local work settings, but also methods that reduce local and global disparities and better address the source of heat exposure, including conservation-informed land-use planning, built environment, and prevention through design approaches. Participation of occupational health experts in transdisciplinary development and integration of these approaches is needed.

Association between work in deforested, compared to forested, areas and human heat strain: An experimental study in a rural tropical environment.

BACKGROUND: With climate change, adverse human health effects caused by heat exposure are of increasing public health concern. Forests provide beneficial ecosystem services for human health, including local cooling. Few studies have assessed the relationship between deforestation and heat-related health effects in tropical, rural populations. We sought to determine whether deforested compared to forested landscapes are associated with increased physiological heat strain in a rural, tropical environment. METHODS: We analyzed data from 363 healthy adult participants from ten villages who participated in a two-by-two factorial, randomized study in East Kalimantan, Indonesia from 10/1/17 to 11/6/17. Using simple randomization, field staff allocated participants equally to different conditions to conduct a 90-minute outdoor activity, representative of typical work. Core body temperature was estimated at each minute during the activity using a validated algorithm from baseline oral temperatures and sequential heart rate data, measured using chest band monitors. We used linear regression models, clustered by village and with a sandwich variance estimator, to assess the association between deforested versus forested conditions and the number of minutes each participant spent above an estimated core body temperature threshold of 38.5°C. RESULTS: Compared to those in the forested condition (n=172), participants in the deforested condition (n=159) spent an average of 3.08 (95% CI 0.57, 5.60) additional minutes with an estimated core body temperature exceeding 38.5°C, after adjustment for age, sex, body mass index, and experiment start time, with a larger difference among those who began the experiment after 12 noon (5.17 [95% CI 2.20, 8.15]). CONCLUSIONS: In this experimental study in a tropical, rural setting, activity in a deforested versus a forested setting was associated with increased objectively measured heat strain. Longer durations of hyperthermia can increase the risk of serious health outcomes. Land use decisions should consider the implications of deforestation on local heat exposure and health as well as on forest services, including carbon storage functions that impact climate change mitigation.

Water quality mediates resilience on the Great Barrier Reef.

Threats from climate change and other human pressures have led to widespread concern for the future of Australia's Great Barrier Reef (GBR). Resilience of GBR reefs will be determined by their ability to resist disturbances and to recover from coral loss, generating intense interest in management actions that can moderate these processes. Here we quantify the effect of environmental and human drivers on the resilience of southern and central GBR reefs over the past two decades. Using a composite water quality index, we find that while reefs exposed to poor water quality are more resistant to coral bleaching, they recover from disturbance more slowly and are more susceptible to outbreaks of crown-of-thorns starfish and coral disease-with a net negative impact on recovery and long-term hard coral cover. Given these conditions, we find that 6-17% improvement in water quality will be necessary to bring recovery rates in line with projected increases in coral bleaching among contemporary inshore and mid-shelf reefs. However, such reductions are unlikely to buffer projected bleaching effects among outer-shelf GBR reefs dominated by fast-growing, thermally sensitive corals, demonstrating practical limits to local management of the GBR against the effects of global warming.

Emissions mitigation opportunities for savanna countries from early dry season fire management.

Savanna fires produce significant emissions globally, but if managed effectively could provide an important mitigation opportunity, particularly in African least developed countries. Here we show global opportunities for emissions reductions through early dry season burning for 37 countries including: 29 countries in Africa (69.1 MtCO2-e yr-1), six countries in South America (13.3 MtCO2-e yr-1), and Australia and Papua New Guinea (6.9 MtCO2-e yr-1). Emissions reduction estimates are based on the successful approach developed in Australia to reduce emissions from savanna fires using global-scale, remotely sensed estimates of monthly emissions. Importantly, 20 least developed countries in Africa account for 74% of the mitigation potential (60.2 MtCO2-e yr-1). More than 1.02 million km2 of savanna dominated protected areas within these countries could be used as pilot sites to test and advance a regional approach to mitigation efforts for savanna fires in Africa. Potential versus actual abatement opportunities are discussed.

Impaired recovery of the Great Barrier Reef under cumulative stress.

Corals of the Great Barrier Reef (GBR) have declined over the past 30 years. While reef state depends on the balance between disturbance and recovery, most studies have focused on the effects of disturbance on reef decline. We show that coral recovery rates across the GBR declined by an average of 84% between 1992 and 2010. Recovery was variable: Some key coral types had close to zero recovery by the end of that period, whereas some reefs exhibited high recovery. Our results indicate that coral recovery is sensitive to chronic but manageable pressures, and is suppressed for several years following acute disturbances. Loss of recovery capacity was partly explained by the cumulative effects of chronic pressures including water quality, warming, and sublethal effects of acute disturbances (cyclones, outbreaks of crown-of-thorns starfish, and coral bleaching). Modeled projections indicate that recovery rates can respond rapidly to reductions in acute and chronic stressors, a result that is consistent with fast recovery observed on some reefs in the central and southern GBR since the end of the study period. A combination of local management actions to reduce chronic disturbances and global action to limit the effect of climate change is urgently required to sustain GBR coral cover and diversity.